An automatic zoning device for ammonia injection pipelines

Abstract

This invention relates to the field of industrial flue gas denitrification technology, specifically an automatic zoning device for ammonia injection pipelines. It includes a main branch pipe vertically arranged on both sides of a main pipeline, branch pipes vertically arranged on the main branch pipes, and guide pipes connected to the branch pipes. A circular plate is fixedly installed inside the branch pipe, with its outer edge extending to and sealing the inner wall of the branch pipe. The lower end of the guide pipe extends out of the branch pipe and bends in the opposite direction to the vertical center line of the branch pipe. The air intake of the side holes is controlled by a sealing mechanism installed inside the branch pipe. Using this invention, firstly, the ammonia gas in the branch pipes can be further refined and diverted using the side holes and guide pipes, thus ensuring more uniform ammonia discharge. Secondly, as needed, the air intake of multiple side holes can be synchronously changed by rotating an inner shaft to ensure that the concentration meets requirements. Furthermore, the air intake of individual side holes can be adjusted as needed.

Description

Technical Field

[0001] This invention belongs to the field of industrial flue gas denitrification technology, specifically an automatic zoning device for ammonia injection pipelines. Background Technology

[0002] Nitrogen oxides (NOx) are among the main air pollutants emitted from stationary sources such as coal-fired power plants and industrial boilers. Selective catalytic reduction (SCR) technology has become the mainstream flue gas denitrification process due to its high denitrification efficiency and reliable operation. This technology injects ammonia (NH3) as a reducing agent into the flue gas, causing it to react with NOx in the flue gas in a catalyst layer to produce harmless N2 and H2O. The ammonia injection grid (AIG) is the core equipment for achieving uniform mixing of ammonia and flue gas; its performance directly determines the denitrification efficiency, ammonia slip rate, and catalyst lifespan of the SCR system.

[0003] Existing ammonia injection grids typically consist of a main ammonia injection pipe and multiple branch ammonia injection pipes connected to the main pipe. Each branch pipe spans the flue gas cross-section, and injection holes or nozzles are spaced along its length on the branch pipes. Ammonia gas is diverted from the main pipe and enters each branch pipe, and is then injected into the flue gas flow channel through the injection holes on the branch pipes. The mixing of ammonia gas and flue gas is achieved by the carrying and diffusion effect of flue gas turbulence.

[0004] However, actual operation shows that the above-mentioned ammonia injection grid structure has a significant problem of uneven ammonia distribution. The fundamental reason is that the lateral (perpendicular to the flue gas flow direction) diffusion capacity of ammonia after it is injected from the branch pipe nozzles is limited. Specifically, the branch pipe itself is a linear injection source, and the nozzle is a point injection source. After leaving the nozzle, the ammonia mainly relies on the turbulent pulsation of the flue gas itself for lateral transport. However, in large-section flues, the spacing between branch pipes is usually large (generally 0.5~1.5 m), while the mixing distance (i.e., residence time) of the flue gas from the ammonia injection grid to the catalyst inlet is relatively limited, resulting in the ammonia not being able to fully diffuse into the area between the two branch pipes within a short distance. As a result, a local high-concentration area is formed near the branch pipe nozzles, while the middle area between two adjacent branch pipes, lacking a direct ammonia supply, relies only on molecular diffusion and weak turbulent mass transfer, resulting in a significantly lower ammonia concentration than near the branch pipes, forming a periodic uneven concentration distribution of "concentration peak at the branch pipe and concentration trough between branch pipes".

[0005] This uneven concentration distribution directly leads to an uneven ammonia-to-nitrogen molar ratio (NH3 / NOx) at the catalyst inlet cross-section: high ammonia concentration areas correspond to excessively high local NH3 / NOx ratios, resulting not only in ammonia waste but also severe ammonia escape; low ammonia concentration areas, due to insufficient reducing agent, result in incomplete denitrification reactions, leading to local NOx emissions exceeding standards. Under long-term operation, the escaped ammonia reacts with SO3 in the flue gas to form ammonium bisulfate (ABS), clogging the downstream air preheater, increasing system pressure drop, and even forcing the unit to operate at reduced load. Actual measurement data shows that due to uneven diffusion of ammonia injection through the branch pipes, the NOx concentration distribution deviation at the reactor outlet can reach tens of mg / m³, and the ammonia escape rate is significantly higher than the design value, seriously affecting the economy and safety of the denitrification system. Summary of the Invention

[0006] This invention provides an automatic zoning device for ammonia injection pipelines to overcome the deficiencies in the prior art.

[0007] This invention is achieved through the following technical solution: An automatic zoning device for ammonia injection pipeline includes a main branch pipe vertically arranged on both sides of a main pipeline, a branch pipe vertically arranged on the main branch pipe, and a guide pipe connected to the branch pipe. A circular plate is fixedly arranged inside the branch pipe, and the outer edge of the circular plate extends to the inner wall of the branch pipe and is sealed to the inner wall. A central hole is opened in the center of the circular plate, and several side holes are opened along its circumference at its edge. The upper end of the guide pipe passes through the corresponding side hole and communicates with the side hole. The lower end of the guide pipe passes through the branch pipe and bends in the opposite direction to the vertical center line of the branch pipe. The air intake of the side holes is controlled by a sealing mechanism arranged in the branch pipe.

[0008] In use, ammonia gas enters the main branch pipe through the main pipeline, then enters the branch pipe through the main branch pipe, and then enters the circular plate through the branch pipe and flows outward through the central hole and the side hole. The ammonia gas at the side hole flows evenly to the perimeter of the branch pipe under the action of the guide pipe, thereby achieving the diversion of ammonia gas at the branch pipe and ensuring that its concentration is quickly and more uniform after dissipation. The sealing mechanism can control the air intake of the branch pipe as needed to ensure that its concentration is more in line with the requirements.

[0009] Preferably, the sealing mechanism includes an air intake control mechanism and a drive mechanism. The drive mechanism includes a central gear ring located at the center of the circular plate. An inner shaft is vertically and upwardly fixedly connected to the central gear ring. The inner shaft passes through a branch pipe and is rotatably connected via a sealed bearing at its exit point. An outer gear ring is fitted around the outer circumference of the central gear ring. A rotating shaft is vertically and rotatably connected to the center of the outer gear ring. The air intake control mechanism controls the air intake volume into the side holes via the central gear ring. Rotating the inner shaft causes the central gear ring to rotate, which in turn causes the outer gear ring to rotate. The rotation of the outer gear ring then drives the air intake control mechanism to control the air intake volume into the side holes. Thus, by rotating one inner shaft, the air intake volume of all side holes can be controlled.

[0010] Preferably, the air intake control mechanism includes a sealing plate, which is fixedly sleeved on the rotating shaft. The sealing plate has an air intake hole with the same diameter as the side hole, and the diameter of the air intake hole is smaller than the diameter of the sealing plate. The rotation of the external gear ring drives the rotating shaft to rotate, which in turn drives the sealing plate to rotate, thereby achieving misalignment between the air intake hole and the side hole. This controls the amount of side hole obstruction, and thus controls the air intake.

[0011] Preferably, the rotating shaft includes an upper shaft, a lower shaft, and a middle tube. An external gear ring is fixedly mounted on the upper shaft, and a sealing plate is fixedly mounted on the lower shaft. The upper end of the middle tube is rotatably connected to the upper shaft via a bearing, and the lower end of the middle tube is fixedly sleeved to the lower shaft. An annular magnet is fixedly connected inside the middle tube. The upper shaft has a spline groove structure and is fitted with a spline shaft. The lower end of the spline shaft passes through the annular magnet and is fixedly connected to a circular magnet. The diameter of the circular magnet is larger than the inner diameter of the annular magnet. The upper end of the spline shaft passes through the upper shaft and is rotatably connected to a lead screw via a bearing. The upper end of the lead screw passes through a branch pipe and is threaded into the branch pipe. During use, the circular magnet and the ring magnet are in contact. Therefore, the rotation of the outer gear ring drives the upper shaft to rotate, the rotation of the upper shaft drives the spline shaft to rotate, the rotation of the spline shaft drives the circular magnet to rotate, and in turn drives the ring magnet to rotate, thus rotating the middle tube. The rotation of the middle tube drives the lower shaft to rotate, which in turn drives the sealing plate to rotate. When it is necessary to adjust the air intake of a certain side hole individually, the lead screw corresponding to that side hole does not move, and the other lead screws are rotated. The rotation of the lead screws drives the spline shaft to move downward, thus separating the ring magnet from the circular magnet, and thus continuing to rotate the inner shaft. The rotation of the other outer gear rings only drives the upper shaft to rotate, while the lower shaft does not rotate, so it does not drive the corresponding sealing plate to rotate. The sealing plate with the lead screw not rotated will follow the rotation of the inner shaft to change the opening amount.

[0012] Preferably, the air intake control mechanism includes an upper-closed tube, the lower end of which is inserted into a side hole and slidably sealed with the side hole. Several air intake grooves are formed circumferentially on the side of the tube. An external thread is formed on the outer side of the inner shaft, which passes through a moving block and is threadedly engaged with the moving block. A vertical shaft is vertically connected to the circular plate, passing through the moving block, which is fixedly connected to the upper end of the tube. Ammonia gas enters the tube through the air intake grooves and then into the side hole. The rotation of the outer gear ring drives the inner shaft to rotate, which in turn drives the moving block to move up and down, thereby moving the tube up and down, thus changing the amount of air intake groove obstruction and consequently changing the air intake volume.

[0013] Preferably, both the outer gear ring and the central gear ring are fixedly provided with horizontal shafts, and the rotating shaft and the inner shaft are respectively vertically connected to the corresponding horizontal shafts.

[0014] Preferably, the lower end of the guide tube is a flared opening that is narrower at the top and wider at the bottom.

[0015] The beneficial effects of this invention are as follows: Firstly, the use of this application can further refine the ammonia gas in the branch pipe by utilizing the side holes and guide tubes, thereby ensuring that the ammonia gas is discharged more evenly. At the same time, as needed, the air intake of multiple side holes can be changed synchronously by rotating an inner shaft to ensure that the concentration is more in line with the requirements. Furthermore, the air intake of a single side hole can be adjusted as needed. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the sealing mechanism in Example 1; Figure 3 This is a schematic diagram showing the distribution of the external gear ring and sealing plate in Example 1; Figure 4 This is a schematic diagram of the sealing mechanism in Example 2; Figure 5 is a schematic diagram of the distribution of the external gear ring and the insertion tube in Example 2; Figure 6 This is a schematic diagram showing the distribution of guide tubes on branch tubes; As shown in the figure: 1. Main branch pipe, 2. Branch pipe, 3. Guide pipe, 4. Circular plate, 5. Side hole, 6. Central gear ring, 7. External gear ring, 8. Inner shaft, 9. Rotating shaft, 10. Sealing plate, 11. Air inlet, 12. Splined shaft, 13. Ring magnet, 14. Circular magnet, 15. Insert pipe, 16. Air inlet groove, 17. Moving block, 18. Trumpet mouth, 91. Upper shaft, 92. Intermediate pipe, 93. Lower shaft. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] An automatic zoning device for ammonia injection pipeline includes Embodiment 1 and Embodiment 2.

[0020] Example 1, as Figure 1-3and Figure 6 As shown, it includes a main branch pipe 1 vertically arranged on both sides of the main pipe, a branch pipe 2 vertically arranged on the main branch pipe 1, and a guide pipe 3 connected to the branch pipe 2. A circular plate 4 is fixedly installed inside the branch pipe 2. The outer edge of the circular plate 4 extends to the inner wall of the branch pipe 2 and is sealed to the inner wall. The circular plate 4 has a central hole in its center and several side holes 5 along its circumference. The upper end of the guide pipe 3 passes through the corresponding side hole 5 and communicates with the side hole 5. The lower end of the guide pipe 3 passes through the branch pipe 2 and bends in the opposite direction to the vertical center line of the branch pipe 2. The air intake of the side holes 5 is controlled by a sealing mechanism installed inside the branch pipe 2. A cross is fixedly installed in the central hole. A circular hole is opened in the center of the cross. A circular shaft passes through the circular hole and is rotatably connected to the circular hole through a bearing.

[0021] In use, ammonia gas enters the main branch pipe 1 through the main pipe, then enters the branch pipe 2 through the main branch pipe 1, and then enters the circular plate 4 through the branch pipe 2 and flows outward through the central hole and the side hole 5. The ammonia gas at the side hole 5 flows evenly to the periphery of the branch pipe under the action of the guide pipe 3, thereby achieving the diversion of ammonia gas at the branch pipe and ensuring that its concentration becomes more uniform after dissipation. The sealing mechanism can control the air intake of the branch pipe as needed to ensure that its concentration meets the requirements.

[0022] The sealing mechanism includes an air intake control mechanism and a drive mechanism. The drive mechanism includes a central gear ring 6 located at the center of the circular plate 4. An inner shaft 8 is vertically and upwardly fixedly connected to the central gear ring 6. The inner shaft 8 passes through the branch pipe 2 and is rotatably connected at the exit point via a sealed bearing. An outer gear ring 7 is fitted around the outer circumference of the central gear ring 6. A rotating shaft 9 is vertically and rotatably connected to the center of the outer gear ring 7. The air intake control mechanism controls the air intake volume into the side holes 5 via the central gear ring 6. Rotating the inner shaft 8 causes the central gear ring 6 to rotate, which in turn causes the outer gear ring 7 to rotate. The rotation of the outer gear ring 7 then drives the air intake control mechanism to control the air intake volume of the side holes 5. Thus, by rotating one inner shaft 8, the air intake volume of all side holes 5 can be controlled.

[0023] The air intake control mechanism includes a sealing plate 10, which is fixedly sleeved on a rotating shaft 9. The sealing plate 10 has an air intake hole 11 that communicates with the side hole 5 and has the same diameter. The diameter of the air intake hole 11 is smaller than the diameter of the sealing plate 10. The rotation of the external gear ring 7 drives the rotating shaft 9 to rotate, which in turn drives the sealing plate 10 to rotate, thereby achieving misalignment between the air intake hole 11 and the side hole 5. This controls the amount of obstruction of the side hole 5, and thus controls the air intake volume.

[0024] The rotating shaft 9 includes an upper shaft 91, a lower shaft 93, and an intermediate tube 92. An external gear ring 7 is fixedly mounted on the upper shaft 91, and a sealing plate 10 is fixedly mounted on the lower shaft 93. The upper end of the intermediate tube 92 is rotatably connected to the upper shaft 91 via a bearing, and the lower end of the intermediate tube 92 is fixedly sleeved to the lower shaft 93. A blind hole is opened on the top surface of the circular plate 4, and the lower shaft 93 passes through the blind hole and is rotatably connected to the blind hole via a bearing. The sealing plate 10 is in contact with the top surface of the circular plate 4. An annular magnet 13 is fixedly connected inside the intermediate tube 92. The upper shaft 91 has a spline groove structure and is fitted with a spline shaft 12. The lower end of the spline shaft 12 passes through the annular magnet 13 and is fixedly connected to a circular magnet 14. The diameter of the circular magnet 14 is larger than the inner diameter of the annular magnet 13. The upper end of the spline shaft 12 passes out of the upper shaft 91 and is rotatably connected to a lead screw via a bearing. The upper end of the lead screw passes out of the branch tube 2 and is threadedly engaged with the branch tube 2. During use, the circular magnet 14 and the annular magnet 13 are in contact. Therefore, the rotation of the outer gear ring 7 drives the upper shaft 91 to rotate, the rotation of the upper shaft 91 drives the spline shaft 12 to rotate, the rotation of the spline shaft 12 drives the circular magnet 14 to rotate, and then drives the annular magnet 13 to rotate, thereby realizing the rotation of the intermediate tube 92. The rotation of the intermediate tube 92 drives the lower shaft 93 to rotate, and then drives the sealing plate 10 to rotate. When it is necessary to adjust the air intake of a certain side hole 5 individually, the lead screw corresponding to the side hole 5 does not move, and the other lead screws are rotated. The rotation of the lead screws drives the spline shaft 12 to move downward, thereby separating the annular magnet 13 from the circular magnet 14, so that the inner shaft 8 continues to rotate. The rotation of the other outer gear rings 7 only drives the upper shaft 91 to rotate, and the lower shaft 93 does not rotate, so it will not drive the corresponding sealing plate 10 to rotate. The sealing plate 10 with the lead screw not rotated will follow the rotation of the inner shaft 8 to change the opening amount.

[0025] Both the outer gear ring 7 and the central gear ring 6 have horizontal shafts fixedly installed inside them, and the rotating shaft 9 and the inner shaft 8 are vertically connected to the corresponding horizontal shafts. The lower end of the guide tube 3 is a flared mouth 18 that is narrow at the top and wide at the bottom, which ensures that the ammonia gas is more diffused and more uniform.

[0026] The application of this technology allows for the further refined distribution of ammonia gas within the branch pipe using the side holes 5 and guide tubes 3, ensuring more uniform ammonia gas discharge. Simultaneously, by rotating an inner shaft 8, the intake volume of multiple side holes 5 can be synchronously changed as needed, ensuring the concentration meets requirements. Furthermore, the intake volume of a single side hole 5 can be adjusted as required. Example 2, as Figures 4-5As shown, compared with the embodiment, the difference lies in that the air intake control mechanism includes an upper closed tube 15. The lower end of the tube 15 is inserted into the side hole 5 and slidably sealed with the side hole 5. Several air intake grooves 16 are opened on the side of the tube 15 along its circumference. The outer side of the inner shaft 8 has an external thread and passes through the moving block 17 and is threadedly engaged with the moving block 17. The circular plate 4 is vertically connected to a vertical shaft, which passes through the moving block 17. The moving block 17 is fixedly connected to the upper end of the tube 15. Ammonia gas enters the tube 15 through the air intake grooves 16 and then enters the side hole 5 through the tube 15. The rotation of the outer gear ring 7 drives the inner shaft 8 to rotate. The rotation of the inner shaft 8 drives the moving block 17 to move up and down, which in turn drives the tube 15 to move up and down, thereby changing the amount of obstruction of the air intake grooves 16 and thus changing the air intake volume.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An automatic zoning device for ammonia injection pipelines, characterized in that: It includes a main branch pipe vertically installed on both sides of the main pipe, a branch pipe vertically installed on the main branch pipe, and a guide pipe connected to the branch pipe. A circular plate is fixedly installed inside the branch pipe. The outer edge of the circular plate extends to the inner wall of the branch pipe and is sealed to the inner wall. A central hole is opened in the center of the circular plate, and several side holes are opened along its circumference at the edge. The upper end of the guide pipe passes through the corresponding side hole and communicates with the side hole. The lower end of the guide pipe passes through the branch pipe and bends in the opposite direction to the vertical center line of the branch pipe. The air intake of the side hole is controlled by a sealing mechanism installed in the branch pipe.

2. The automatic zoning device for ammonia injection pipelines according to claim 1, characterized in that: The sealing mechanism includes an air intake control mechanism and a drive mechanism. The drive mechanism includes a central gear ring located at the center of the circular plate. An inner shaft is vertically and upwardly fixedly connected to the central gear ring. The inner shaft passes through a branch pipe and is rotatably connected to the branch pipe through a sealed bearing. An outer gear ring is fitted around the outer circumference of the central gear ring. A rotating shaft is vertically and rotatably connected to the center of the outer gear ring. The air intake control mechanism controls the air intake volume entering the side hole via the central gear ring drive.

3. The automatic zoning device for ammonia injection pipelines according to claim 2, characterized in that: The air intake control mechanism includes a sealing plate, which is fixedly sleeved on the rotating shaft. The sealing plate has an air intake hole with the same diameter as the side hole, and the diameter of the air intake hole is smaller than the diameter of the sealing plate.

4. The automatic zoning device for ammonia injection pipelines according to claim 3, characterized in that: The rotating shaft includes an upper shaft, a lower shaft, and a middle tube. An external gear ring is fixedly mounted on the upper shaft, and a sealing plate is fixedly mounted on the lower shaft. The upper end of the middle tube is rotatably connected to the upper shaft via a bearing, and the lower end of the middle tube is fixedly sleeved to the lower shaft. An annular magnet is fixedly connected inside the middle tube. The upper shaft has a spline groove structure and is fitted with a spline shaft. The lower end of the spline shaft passes through the annular magnet and is fixedly connected to a circular magnet. The diameter of the circular magnet is larger than the inner diameter of the annular magnet. The upper end of the spline shaft passes through the upper shaft and is rotatably connected to a lead screw via a bearing. The upper end of the lead screw passes through a branch pipe and is threaded into the branch pipe.

5. The automatic zoning device for ammonia injection pipelines according to claim 2, characterized in that: The air intake control mechanism includes an upper closed tube, the lower end of which is inserted into a side hole and slidably sealed with the side hole. Several air intake grooves are opened on the side of the tube along its circumference. The outer side of the inner shaft is provided with an external thread and passes through the moving block and is threadedly engaged with the moving block. The circular plate is vertically connected to a vertical shaft, which passes through the moving block. The moving block is fixedly connected to the upper end of the tube.

6. The automatic zoning device for ammonia injection pipelines according to claim 2, characterized in that: Both the outer gear ring and the central gear ring are fixedly equipped with horizontal shafts, and the rotating shaft and the inner shaft are respectively vertically connected to the corresponding horizontal shafts.

7. The automatic zoning device for ammonia injection pipelines according to claim 2, characterized in that: The lower end of the guide tube is a flared opening that is narrower at the top and wider at the bottom.

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